common: Add Milli Kelvin conversion macros

Add macros to convert to and from milli kelvin and various temperature
units. Utilize round_divide for more accurate conversions.

BUG=b:176994331
TEST=Unit test
BRANCH=None

Change-Id: Ie6750b9d2d2b8093fdf9c14f904382e91d8d95bb
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3078051
Reviewed-by: Keith Short <keithshort@chromium.org>

5 files changed, 65 insertions, 3 deletions

diff --git a/common/battery.c b/common/battery.c
index c24bf59da9..6791e4d3a2 100644
--- a/common/battery.c
+++ b/common/battery.c
@@ -15,6 +15,7 @@
 #include "gpio.h"
 #include "hooks.h"
 #include "host_command.h"
+#include "math_util.h"
 #include "timer.h"
 #include "usb_pd.h"
 #include "util.h"
diff --git a/common/build.mk b/common/build.mk
index caed246a74..7c505c066f 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -43,7 +43,7 @@ common-$(CONFIG_BACKLIGHT_LID)+=backlight_lid.o
 common-$(CONFIG_BASE32)+=base32.o
 common-$(CONFIG_BLINK)+=blink.o
 common-$(CONFIG_DETACHABLE_BASE)+=base_state.o
-common-$(CONFIG_BATTERY)+=battery.o
+common-$(CONFIG_BATTERY)+=battery.o math_util.o
 common-$(CONFIG_BATTERY_FUEL_GAUGE)+=battery_fuel_gauge.o
 common-$(CONFIG_BLUETOOTH_LE)+=bluetooth_le.o
 common-$(CONFIG_BLUETOOTH_LE_STACK)+=btle_hci_controller.o btle_ll.o
diff --git a/include/common.h b/include/common.h
index 03e1b19d55..373663ea88 100644
--- a/include/common.h
+++ b/include/common.h
@@ -218,8 +218,22 @@
 /* There isn't really a better place for this */
 #define C_TO_K(temp_c) ((temp_c) + 273)
 #define K_TO_C(temp_c) ((temp_c) - 273)
-#define CELSIUS_TO_DECI_KELVIN(temp_c) ((temp_c) * 10 + 2731)
-#define DECI_KELVIN_TO_CELSIUS(temp_dk) ((temp_dk - 2731) / 10)
+/*
+ * round_divide is part of math_utils, so you may need to import math_utils.h
+ * and link math_utils.o if you use the following macros.
+ */
+#define CELSIUS_TO_DECI_KELVIN(temp_c) \
+	(round_divide(CELSIUS_TO_MILLI_KELVIN(temp_c), 100))
+#define DECI_KELVIN_TO_CELSIUS(temp_dk) \
+	(MILLI_KELVIN_TO_CELSIUS((temp_dk) * 100))
+#define MILLI_KELVIN_TO_MILLI_CELSIUS(temp_mk) ((temp_mk) - 273150)
+#define MILLI_CELSIUS_TO_MILLI_KELVIN(temp_mc) ((temp_mc) + 273150)
+#define MILLI_KELVIN_TO_KELVIN(temp_mk) (round_divide((temp_mk), 1000))
+#define KELVIN_TO_MILLI_KELVIN(temp_k) ((temp_k) * 1000)
+#define CELSIUS_TO_MILLI_KELVIN(temp_c) \
+	(MILLI_CELSIUS_TO_MILLI_KELVIN((temp_c) * 1000))
+#define MILLI_KELVIN_TO_CELSIUS(temp_mk) \
+	(round_divide(MILLI_KELVIN_TO_MILLI_CELSIUS(temp_mk), 1000))
 
 /* Calculate a value with error margin considered. For example,
  * TARGET_WITH_MARGIN(X, 5) returns X' where X' * 100.5% is almost equal to
diff --git a/test/math_util.c b/test/math_util.c
index b45de1a29d..6482888e55 100644
--- a/test/math_util.c
+++ b/test/math_util.c
@@ -78,12 +78,58 @@ static int test_rotate(void)
 	return EC_SUCCESS;
 }
 
+test_static int test_round_divide(void)
+{
+	/* Check function version */
+	TEST_EQ(round_divide(10, 1), 10, "%d");
+	TEST_EQ(round_divide(10, 2), 5, "%d");
+	TEST_EQ(round_divide(10, 3), 3, "%d");
+	TEST_EQ(round_divide(10, 4), 3, "%d");
+	TEST_EQ(round_divide(10, 5), 2, "%d");
+	TEST_EQ(round_divide(10, 6), 2, "%d");
+	TEST_EQ(round_divide(10, 7), 1, "%d");
+	TEST_EQ(round_divide(10, 9), 1, "%d");
+	TEST_EQ(round_divide(10, 10), 1, "%d");
+	TEST_EQ(round_divide(10, 11), 1, "%d");
+	TEST_EQ(round_divide(10, 20), 1, "%d");
+	TEST_EQ(round_divide(10, 21), 0, "%d");
+
+	/* Check negative conditions */
+	TEST_EQ(round_divide(-10, 6), -2, "%d");
+	TEST_EQ(round_divide(10, -6), -2, "%d");
+	TEST_EQ(round_divide(-10, -6), 2, "%d");
+
+	return EC_SUCCESS;
+}
+
+test_static int test_temp_conversion(void)
+{
+	TEST_EQ(C_TO_K(100), 373, "%d");
+	TEST_EQ(K_TO_C(100), -173, "%d");
+
+	TEST_EQ((int)CELSIUS_TO_DECI_KELVIN(100), 3732, "%d");
+	TEST_EQ(DECI_KELVIN_TO_CELSIUS(100), -263, "%d");
+
+	TEST_EQ(MILLI_KELVIN_TO_MILLI_CELSIUS(100), -273050, "%d");
+	TEST_EQ(MILLI_CELSIUS_TO_MILLI_KELVIN(100), 273250, "%d");
+
+	TEST_EQ(MILLI_KELVIN_TO_KELVIN(5000), 5, "%d");
+	TEST_EQ(KELVIN_TO_MILLI_KELVIN(100), 100000, "%d");
+
+	TEST_EQ(CELSIUS_TO_MILLI_KELVIN(100), 373150, "%d");
+	TEST_EQ(MILLI_KELVIN_TO_CELSIUS(100), -273, "%d");
+
+	return EC_SUCCESS;
+}
+
 void run_test(int argc, char **argv)
 {
 	test_reset();
 
 	RUN_TEST(test_acos);
 	RUN_TEST(test_rotate);
+	RUN_TEST(test_round_divide);
+	RUN_TEST(test_temp_conversion);
 
 	test_print_result();
 }
diff --git a/test/sbs_charging_v2.c b/test/sbs_charging_v2.c
index 520db7bb20..bdca592d6c 100644
--- a/test/sbs_charging_v2.c
+++ b/test/sbs_charging_v2.c
@@ -12,6 +12,7 @@
 #include "gpio.h"
 #include "hooks.h"
 #include "host_command.h"
+#include "math_util.h"
 #include "power.h"
 #include "task.h"
 #include "test_util.h"